1. Field of the Invention
The present invention relates to an optical disc device including time search function of performing playback from specified time.
2. Description of Related Art
In recent years, as a video device recording and playing back videos and audios, an optical disc device is typically frequently used. As a recording medium of the optical disc device, there are recently a DVD (Digital Versatile Disc), a BD (Blu-ray Disc), and an HD DVD (High Definition DVD). Then one of features of the optical disc is that playback can be done quickly from a desired section. For this, various methods have been suggested.
For example, JP-A-2006-202402 discloses an information playback device and an information playback method including for each data unit a table where addresses of a plurality of data units to be played back within a time range including the current time are recorded. In these device and method, the number of data units to be interlace-played back in accordance with playback speed is obtained, it is judged whether the address in accordance with the obtained number in the table is valid or invalid, when the address is valid, playback is performed based on this valid address, and when the address is invalid, playback is performed based on a valid address in the addresses of the data unit to be played back at time closer to the current time than the playback time for the data unit with this invalid address.
JP-A-2007-80329 discloses a still image switching position search device for a disc provided with: a reading part for reading recording information from a disc where management information related to video data including a moving image or a still image recorded in a user data area; a judge part for receiving the management information read by the reading part, obtaining title information on the video data, and based on address data of a top video object unit in cell information forming each title, judging whether or not still image information is included in the video data; and a control part for, when the still image information is included, obtaining from the management information on playback position time of this still image information and controlling a display part to display on a display screen a title number of each still image information and time of its switching position thereof.
JP-A-2005-346911 discloses a recording device in which a system controller performs playback control based on address information which indicates video information to be actually played back in angle block playback or parental block playback, and which is included in VOB unit search information included in DSI data separated from a demodulated demodulation signal by a system buffer.
JP-A-2004-213728 discloses a DVD playback device which, when playback position is specified by time, reads C_PBTM where playback time for each cell included in PGCI is written, makes comparison with the specified time while sequentially adding each C_PBTM to detect a cell including the specified time, obtains a difference between the specified time and time at the top of the cell including the specified time, defines as a temporary VOBU number a value obtained by dividing the obtained difference by 0.5 and then adding 1 to the obtained value, reads C_ELTM where playback time of each VOBU included in the cell is written, adds together C_ELTM up to the obtained temporary VOBU number to obtain total elapse time, makes comparison with the specified time while adding or subtracting C_ELTM in accordance with VOBU numbers before and after the total elapse time to detect the VOBU agreeing with the specified time, and performs playback from a top address of the detected VOBU.
JP-A-2006-66025 discloses an optical disc reproduction device in which, upon time search request, a search destination address is determined based on analyzed search time, a navigation pack for the detected search destination address is obtained, when there is no video data in the obtained navigation pack, a top address of a front stage video object unit having video data is obtained from the data search information included in the obtained navigation pack, data of the obtained top address is read and only the video data is obtained based on general information of the data search information included in the navigation pack, and a still image corresponding to audio data is outputted.
In performing time search in conventional optical disc devices including those described in the above five publications, playback has been practiced from the top of a VOBU (video object unit) including time for search destination. It is because playback can be done only in units of VOBUs. Thus, when the time for search destination is located at the rear of the VOBU, playback is started at a position a maximum of approximately 0.5 seconds before specified time.
For example, assuming that when the time for the specified search destination is 1h00m00s00f (1 hour 0 minutes 0 seconds 0 frame), the top of a VOBU including this time is 0h59m59s17f, playback is started from there. At this point in time, when playback elapse time is OSD-displayed, playback for the OSD display is started in a state of 1h00m00s, and processing is performed so that the OSD display is updated to 1h00m01s when playback position at 1h00m01 s00f has been reached. That is, time until when the OSD display at 1h00m00s is updated to 1h00m01s is actually one second or more.
As described above, conventionally, a difference between specified time and actual playback start time has been compensated by such processing that deludes OSD display. Therefore, accurate time search has not been necessarily achieved.